1. Field of the Invention
This invention relates to modification of surface properties, particularly surface wetting properties, of various materials, including polymer films, textile fibers, cellulose. Such treatments are typically carried out in preparation to further processing or treatment of the materials, such as dyeing or impregnation of fibers and fabrics.
It is known that surface properties of materials such as textile fabrics, polymer films, paper, cellulose, etc. can be modified by exposure of the material to either a low temperature, low pressure gas plasma or to a corona discharge. The processes performed at low pressure are more efficient than those performed in the corona discharge. Unlike corona discharge treatment, exposure to low pressure plasma discharge does not significantly raise the temperature of the treated material, thereby preserving the physical condition and properties of the material.
2. State of the Prior Art
Previous methods of improving absorbency of strips made of fibers include treatment in a corona discharge, as exemplified by French patent 2,333,084. A disadvantage of this method is that the corona discharge is substantially less effective than low pressure plasma, and relatively prolonged treatment times are necessary to sufficiently improve the capillary absorption of the fabrics.
In U.S. Pat. No. 4,338,420 improved wetting of low pressure polyethylene films is obtained by treatment in a low temperature plasma of inorganic gas such as O.sub.2, Ar, N.sub.2, or air. The effect of the plasma on the film is weak, however. After plasma treatment the wetting angle is 43 to 60 degrees for polyethylene and 55 to 65 degrees for polypropylene.
Japanese patent 61-247740 describes polyolefine activation before dyeing by treatment in oxygen plasma activated by radiofrequency power at 10 Mhz, at a pressure of 0.3-0.5 Torr, with a treatment time of 5-30 sec. The effect of the plasma treatment on the subject material is insufficient, however.
USSR patent 1030445 addresses the treatment of textile materials containing polyester fibers, including treatment in a solution containing 5-25 g/l metal hydroxide for 2-5 minutes; followed by treatment in a glow discharge plasma with density 0.014-0.27 A/cm2, pressure=0.02-0.04 Torr, T=60-90 sec to achieve enhanced hydrophilic properties. However, the pretreatment in solution considerably increases total treatment time, and the plasma effect on the treated material is insufficient.